Fire-retardant composition containing an anion exchange resin



CZEZA 5s zmeauacs UNITED STATES I i D FIRE-RETARDANT COMPOSITIDNCONTAIN- I ING AN ANION EXCHANGE RESIN Walter Juda and Grlnnell. Jones, Cambridge, Mass and Nathaniel Altman, Kcw Gardens, N. Y., assignors, by mesne assignments, to Alb! Manufacturing (30., Incorporated, a corporaiion of Connecticut No Drawing. Application May 22, 1946, Serial No. 671,660

14 Claims.

This invention relates to the improvement of. the fire and heat resistance of materials and is more particularly concerned with fire-retardant and potentially heat-insulating nitrogen-containing resinous compositions. The invention also relates to methods of employing these compositions. and of processing materials to impart thereto fire and heat resistance. The invention further comprises the products'obtained by such processing.

The most efficient fire-retarding compositions of the prior art usually contain ifiorganlc'fireretarding compounds which are admixed, in some cases, with various organic materials. The inorganic fire-retardants retain in these compositions their inherent physical and chemical characteristics such as acidity or alkalinity, crystal-- linity, and others, which greatly limit the usefulness of these compositions.

For example, strong inorganic acids, in particular phosphoric acids, are good fire retardants.

but compositions containing the free acids in any appreciable amount are water-soluble, do not dry satisfactorily and usually impair materials to which they are applied; and salts of phosphoric acid, in particular ammonium phosphate, render the compositions water-soluble, and in many cases hard and brittle.

The fire-retarding compositions of the prior art may be divided into two classes: the first comprises compositions in which at least one of the ingredients essential in providing fire-retardance is.-water-soluble; the second class comprises water-insoluble compositions. To the first class belong the compositions based on alkali silicates, and the compositions comprising inorganic water-soluble fireproofing compounds such as inorganic acids and salts, especially alkali and ammonium phosphates, sulfates, sulfamates, borates, halides, etc. To the second class belong compositions which contain water-insoluble inorganic fire-proofing compounds such as antimony oxide; and heavy metal stannates, andcmmmsi tions containing organic materials such as chlorinated rubber, chlorinated parailins and similar chlorinated organic materials.

it is well-known that the best water-soluble compositions are considerably more effective in flre-retardance than the best water-insoluble compositions. For example, compositions in .2 which a, soluble inorganic compound such as ammonlum phosphate, ammonium sulfate, etc, is mixed with a urea-formaldehyde resin and preferably with a carbohydrate, when exposed to heat, form a carbonaceous foam of outstanding fire-retarding and heat-insulating properties.

' This type of composition is far superior in fireretarding qualities to any of the other compositions but it lacks water-resistance and it is somewhat brittle because of the crystalline character of the inorganic salts used.

If both water-resistance and good flexibility are desired, the alternatives suggested by the prior art therefore are compositions containing chlorinated parafilns and the like, and insoluble compounds such as heavy metal stannates or antimony oxides. But these compositions are very inferior in fire resistance. They are not potential heat insulators and are therefore entirely unsuitable for protecting non-combustible materials, such as metal,- from damage by heat. They are unsuitable for use with wood, insulating board, etc., because they are not effective enough to impart a sufllcient measure of fire-retardance to such materials. Their main use is on fabrics. but even there they require heavy impregnations to pass fire tests. Finally, they are quite expensive.

An object of this invention is to provide improved fire-retardant resinous compositions having none of the undesirable physical and chemical characteristics inherentin inorganic fireretarding compounds but at the same time having superior fire-retardant and potential heatinsulating properties.

Another object of the invention is to provide improved methods 01' processing materials to impart the properties of fire and heat resistance thereto.

. Another object of the invention is to provide coated or impregnated products having enhanced fire and heat resistance.

Another object of the invention is to provide improved products consisting mainly of normally combustible materials but which have improved fire resistant properties. I

In general we have discovered that reaction products of basic nitrogen-containing anionexchange or acid-adsorbent resins with nonoxidizing inorganic acids. which reaction prodbility than the divalent acids.

note will hereinafter be called resin salts, are substantially less inflammable than the basic resins themselves and areicapable of forming a fire-retardant and heat-insulating carbonaceous mass when subjected to elevated temperatures, for example, of the order of temperatures of flaming wood, wall board and the like, burning in'air. By "non-oxidizing acids we mean the monovalent hydrogen halides and the polyvalent acids; by so defining and limiting the term "non-oxidizing" in this specification and in the appended claims we disclaim those acids, particularly nitric acid. chloric acid, perchloric acid and the like, which are such strong oxidants that they tend to increase rather than reduce the combustibility of the basic resin. As basic resins we may use condensation products of amines or other organic bases with aldehydes, phenols or other condensing agents, as more fully described below.

To form resin salts which are stable towards leaching, we prefer to use strong non-oxidizing inorganic acids havin a dissociation constant of or higher. As used herein, the term "acid" includes acid salts. We have found that the divalent acids form more stable resin salts than the univalent acids, and that the triand tetravalent acids -form resin salts of even better sta- While hydrochloric acid, and hydrobromic acid, for example, form, with the basic resin, resin salts of reduced inilammability which are effective fire-retardants to a greater or less extent, and sulfuric acid forms resin salts somewhat better in this respect, we

have found that phosphoric acids yield resin salts with the basic resins which are much superior. They are substantially non-inflammable at flame temperatures of, say, 750 C. or less, and possess excellent fire-retarding and potentially heatinsulating properties yielding on exposure to flame temperatures a. carbonaceous, heatinsulating mass which is resistant to combustion. These resin salts are highly stable; in some instances they resist not only leaching by water and by monoor divalent acids, but even by alkalis and by organic solvents.

As the amount of acid combined per gram of basic resin is increased, the effectiveness of the product increases. Thus we have found generally that not less than one milliequivalent and preferably at least two milliequivalents of acid per gram of basic resin is required to make a product of practical value. Consequently, while the reaction products of the basic resins with strong non-oxidizing inorganic acids in generalpossess reduced inilamrnability and are suitable fire-retardants for some purposes, we prefer those reaction products of basic nitrogen-containing resins with phosphoric acids, which contain at least two milliequival'ents of phosphoric acid per gram of basic resin. Usually, but not necessarily, the basic resins do not combine with more than milliequivalents of phosphoric acid per gram of basic resin.

We have found that combustible materials such as wallboard, flbreboard, cardboard, wood including plywood, fabrics, paper, etc., can be rendered less inflammable or substantially fireproofed by coating and/or impregnating them with the resin salt. The treatment can be carried out, for example, by first dispersing the insoluble, heat-cured, finely divided resin salt in a liquid vehicle containing a film-forming bonding agent such as a drying oil, an alkyd or other film forming resin. a cellulose derivative, for ex- 4 ample ethyl cellulose, methyl cellulose, cellulose acetate, and the like; then applying said dispersion to the combustible material by painting, sprayin or other suitable means and then drying the treated material until a solid fire-retardant film is formed on the treated material. The combustible material can also be treated by applying the resin salts in an early stage of their manufacture. For example, the resin forming ingredients may be reacted in water in the presence of the strong non-oxidizing inorganic acid, the combustible material may be treated with the aqueous solution or dispersion of the resin salt in a low state of polymerization in which it is still capable of remaining dissolved or suspended as a colloid, and in which state the resin salt possesses good bonding and film-forming properties, and the treated material may then b heatcured. In general there is formed by this treatment a protective fire-retardant solid film onthe combustible materials. In the case of fabrics, paper, wood, or other porous combustible materials, the aqueous solution or dispersion of the resin salt may also be used as an impregnating liquid. When so used the fire retardant resin salt is deposited in and on the combustible porous material which is thereby impregnated. Use as a fire-retardant adhesive may also be made of the resin salt in a low state of polymerization to glue paper, veneer or other laminated materials to a surface. In this case the paper or the like and, if desired, the surface to which it is to be glued, are treated with the aqueous dispersion of the resin salt as above, the two surfaces are pressed together and the film between the surfaces is cured as, for example, by heating. When so used the bonding properties of the aqueous resin salt dispersion-may be enhanced by adding to the dispersion a conventional bonding agent such as'wheat paste and the like. We have also found that incombustible materials, particularly metals, may advantageously be coated with resin salts by the same methods of application, whereby use is made or the potentially heat-insulating properties of the coating for protecting the metal from damage by heat or for reducing the heat transmission through it when exposed to flame temperatures.

It should be noted that the term acid adsorbent is somewhat misleading because the basic resins do not merely adsorb acids but appear actually to react chemically with the acids.

In fact, the mechanism of acid adsorption is probably mainly that of chemical reaction with some characteristics of adsorption. Consequently when the term acid adsorbent" is used in this specification, it is understood that it includes a chemical reaction. Furthermore, we use the terms change resin interchangeably in this specification and in the claims. We wish it understood that the resins so designated are intended to include basic resins capable of forming resin salts from which the acid is no longer completely removable by treatment with an alkali or another ac d.

It is well known that in recent years many synthetic resinous amon-exchangers have been prepared and are being used mainly for water purification. The preparation and use of these resins in water purification and allied fields has been described in detail in the chemical literature. For exam-pie, reference is made to United States Patents Nos. 2,151,883, 2,198,874, 2,246,527,

acid-adsorbent resin and anion-ex- Lamas-w a csaos's 2,356,151 and 2.36.088. Acid-adsorbent resins are obtained in general when basic nitrogen-contalning organic compounds such as amines, or

guanidine, and the like, are condensed with aldehydes, hydroxy aldehydes (sugars, starch, etc.) or with mixtures of aldehydes and ketones, un-

' der such conditions that not all of the basic groups are linked to aldehyde residues in the formation of the resinous structure; that is, only resins containing free basic groups exhibit anionexchanglng properties. Typical acid-adsorbent or anion-exchange resins suitable for the for-mation of fire-retardant and potentially heat-insulating compositions with strong inorganic acids include the Iollowing classes:

Resins made by condensing (l) meta-substituted aromatic amines or aromatic polyamines with aldehydes and/or carbohydrates with or without ketones;

(2) aliphatic polyalkylene polyamines with aldehydes and ketones;

(3) aliphatic .polyalkylene polyamines with phenols and-aldehydes;

(4) a strongly basic derivative of cyanamide, with a weakly basic derivative of cyanamide, and

g with an aldehyde, as more fully defined below.

In addition, a carbohydrate may be included.

As aldehydes we use aliphatic aldehydes, particularly formaldehyde or a source of formalde hyde such as paraformaldehyde, trioxymethyiene and the like, a'cetaldehyde; or cyclic aidehydes such as iurfural and the like. Carbohydrates (sugar, starch, etc.) which are mentioned specifically whenever they may be used and which may or may not contain aldehyde CHO) groups, are not necessarily equivalents of aldehydes in forming fire-retardant resin salts.

A great variety of operative anion-exchange resins or resinous mixtures may be prepared by varying the above components, or by co-con- -densing them with other resin forming ingredients; for example, anion exchangers may be formed in which strongly basic quaternary ammonium hydroxides are used in place of, or in addition to, an organic amine or guanidine or the like; or hydroxy aldehydes and hydroxyketones, in particular carbohydrates "of this invention. f

Preferably the resins are combined with as large an amount of acid as possible. In general, resins of the'above types will combine with 1 to about 15 milliequivalents of acid per gram of resin. In some cases it is possible to use considerably more acid, for example. as much as 25 milliequivalents or more per gram of resin.

While we havefound that the anion-exchange and acid-adsorbent resins in general are suitable for the preparation of vfire-retardant resin salts, we have found that the resins of class (4) form more stable resin salts which are generally better fire-retardants. In this preferred class of resins we find it necessary to use an aldehyde as one.

of the resin-forming agents. While it is possible to use a carbohydrate in'addition to the aldehyde,

we cannot use a carbohydrate inplace or the aldehyde because the resulting mixture containingno aldehyde is no longer a fire-retardant resin salt as defined herein: it tends to crystallize. thereby losing its resinous characteristics to a large extent. and possesses interior water resistance.

This preferred class of resins comprises cocondensation products of a. strongly basic derivative oi cyanamide and o! a weakly basic derivative otcyanamide, with an aldehyde. Cyanamide has the formula CmI-Iz and its structure may be written NEG-{NR2 or HN=C=NH.. Some ot'the more important derivatives of cyanamide which may be used according to this invention are shown in the iollowing diagram:

Weakly but: derivative:

lmbamylgmnidine o d1 smidine or smurlum) The strongly basic character of guanidine is generally attributed to the fact that the guanidinium ion C(NHs): resonates between three equivalent structures The resonance energy of these three structures makes the guanidinium ion, more stable than guanidlne itself, thereby favoring'the right side 01 the equilibrium Hot-chit where X may be 0, 5,- NH or N- this group accepts resins. It should be noted that the strongly basic derivative of cyanamide contains. in addition to the basic resonating structures, this same sidehyde-reactive group. While we do not limit ourselves to any particular theory. we believe that typical resinous co-condensation structures or the preferred class (4) may be illustrated by the plausible structural Formula. I for a product made from guanidinc, urea and tormaldehyde, and II tor a product made from guanidlne, melamine and formaldehyde:

i o=rrn cnir/ \N and 1 m, on, N/ a; on, N i is is: t i \N/ l g g i \N/ I It will be noted that in these structures the guanidine segment can resonate, when attracting a hydrogen ion, between the two equivalent In a similar cit-condensation structure 1-carbamylguanidinc (also called dicyandiamide or guanylurea) gives an acid adsorbent segment which when reacted with H may be written Thus, in general, as strongly basic derivatives of oyanamide, we may use compounds which will give, when condensed with an aldehyde and with a weakly basic derivative of cyanamidc, an acid adsorbent resinous structure containing the grou sis-i=1 where 1: may be an oxygen atom, a sailor atom. an NH group or N--. This group of weakly mic compounds which is termed weakly basic derivatives o! cyanamide in this specification and the diamide, melamine and the like. that is in general compounds containing the said reactive group which will term, with an aldehyde. in the resinous. structure. the cement The preferred resins of class (4) usually have a higher nitrogen content than the resins oi the other three classes; we believe that this high nitrogen content contributes to reduction or the combustibility oi the basic resin itself, and, in conjunction with the inorganic acid, tends to make a resin salt which forms a more voluminous and less combustible carbonaceous mass on exposure to names.

The fire-retardant and potentially heat-insulating resin-salt when heat-cured, is a solid substantiallywater-lnsoluble product which is very difierent in chemical nature from the mere mixtures of an acid or a salt with a resin. Thus compositions containing mere mixtures oi! soluble acids or salts with or without resins or other organic materials are not resistant to leaching;

I in such mixtures the acid or the salt retains its physical and chemical characteristics such as acidity, liquid or crystalline state, melting point, etc. In the resin salt, on the contrary, the acid. or acid salt, is chemically combined, thereby losing its objectionable chemical and physical characteristics. but retaining its power to convert the resin into a carbonaceous mass when subjected to heat.

To prepare a fire-retardant resin salt. it is possible to condense the resin in the presence of the acid or acid salt; or the' resin may be prepared in advance and then contacted with an aqueous solution of the acid.-

In order to obtain a high degree of fireretardance we have found that it is advantageous to apply the resin salt to combustible materials while the resin salt is still in a so-called watersoluble or incompletely polymerized state, and then cure the resin on or in the treated material. More particularly, highly combustible materials such as plywood, flbreboard and wallboard which require a high de ree or fire protection are pref= erably coated with an aqueous solution of the resin salt and then subjected to polymerizing conditions, for example to heat to eflect the curing oi the resin salt in situ. When the resin salts or the preferred resins or class (4) with phosphoric acids are so used they form a continuous, strongly adhering illm oi excellent fire-retarding properties. when termed in this manner, the resinous coating on the combustible material i especially eil'ective in its fire-retardant action, since it is not interfered with by the presence of other materials, such as film-forming bonding agents or fillers which are usually combustible organic materials or inert inorganic diiucnts and which therefore tend to decrease somewhat the effectiveness of the coating.

The degree or fire protection may be controlled by varying the thickness of the film. The thicker the film, or the greater the weight of coating per unit area, the better the protection.

In the water-soluble stage many resin salts tend to polymerize slowly on standing so that it is usually necessary to use them reasonably promptly after they have been prepared. This appended claims includes urea, thiourea, dicyan- 75 is perfectly possible in factory applications. For

example, in the manuiacture or wallboard, solutions of resin salts may be made up in the moming for a days production or wallboard. The solutions may be applied to the wallboard in'a late stage of its manufacture.

However, it may not always be practical to use the above method oi. application. In many instances it is desirable to supply to the user a product which is stable on standing and which he may apply whenever convenient. For this purpose we polymerize the resin salt to a solid state, in which it is stable. We then disperse the solid resin salt in a finely-divided state in a liquid vehicle comprising a film-forming bonding agent,

with or without a volatile thinner. Combustible materials can be coated with these compositions by spraying or paintaing or dipping or other suitable means. Upon evaporation of the thinner, a

film is formed, which makes the solid resin salt ventional paint thinners and driers may advantageously be used to complete the composition.-

More suitable film-formers than drying oils are film-forming resins, particularly alkyd resins. Among the alkyd resins we prefer the class of drying oil modified alkyds. These resins are not very combustible when well dried .lout they do 1c This dispersion gelled suddenly when heated on a steambath tor about 15 minutes. The sol was out into small pieces and dried at about 105 C. The dried gel was then washed with water, to remove any excess of unbound phosphoric acid, until the wash water was phosphate iree. Thus was obtained a resin phosphate of excellent fi.reretardant and potentially heat-insulating properties. The resin phosphate is remarkably waterinsoluble, the phosphoric acid being chemically bound to the resin. Thus the solid product obtained is very different item a mere mixture of phosphoric acid, or one or its salts with a resin. It is substantially water-insoluble. It resists treatment by HCl, H2504, and H31, showing that the resin phosphate is more stable than the sulfate, hydrochloride or hydrobromide. It is substantially irreversible in the sense that a substantial fraction of the phosphoric acid combined with the resin can no longer be removed by treatment with alkali. The product, when subjected for two minutes to a temperature of 750 C. in an electric iurnace, expanded to a carbonaceous mass having a volume several times that of the interfere somewhat with the formation of the formers are cellulose others and cellulose esters in general, and especially methyl cellulose, ethyl cellulose, cellulose acetate and the like. These cellulose derivatives maybe dissolved in an appropriate solvent (water, alcohol. etc.) and then the finely divided, solid, fully polymerized resin salt may be dispersed inthis solution. The cellulose derivatives interfere less with the efiectiveness of the resin salt than the drying oils or alkyds. While we have mentioned the above named film-forming agents as typical examples, it is clear that other film-forming agents may be used without departing from the scope or this invention.

Pigments and fillers may be added if desired.

The-following specific examples illustrate how the invention may be carried out.

Example I.This example illustrates how a. preferred resin salt may be made and used according to this invention.

(a) 119 grams of guanidine carbonate and 126 grams of melamine were a ded to grams of aqueous formlaldaiyde (37%). The ratio of the resin-iormingin'grc dientswas thus .4 mols of formaldehyde to 2 mols of combined guanidine and melamine and thus. a 2:1 ratio between the formaldehyde and the cyanamide derivatives. The mixture was allowed to stand for 20 minutes. Then 42.5 cc. of concentrated phos horic acid (85% HsPO-i) was added in sm portions on the evolution of carbon dioxide stopped. The mixture was agitated continuously until an aqueous, slightly viscous dispersion was formed.

original sample and this expanded mass remained substantially intact throughout, the test.

(b) The slightly viscous aqueous dispersion obtained in (a) prior to gelling by heat was applied to one side of a wallboard by brushing. The wet board was heated at about 90 C. for three hours, whereby the water was evaporated and a uniform heat cured resin salt coat formed on the board. The coatedboard showed a greatly reduced inflammability on the coated side.

(0) 25 parts by weight of guanidine carbonate, 25 parts by weight 01' melamine and 62 parts by weight or aqueous formaldehyde (37%) were added to 60 parts of water. The ratio of the resin-forming ingredients wasthus 1% mols of formaldehyde to '1 mol of combined gu dine caimnd melamine. To this mixture was an very gradually and with thorough stirring, 42.5 parts by weight of phosphoric acid In a typical factory test application, a fibreboard was sprayed with this resin salt solution. The treated wet fibreboard was then run through a hot air oven approximately 60 it. long, heated to approximately 400 E, at a rate of 56 it. or board per minute.

In another factory test application an untreated fibreboard was preheated by passage through a drying oven, was then sprayed with the resin salt solution and immediatelythereaiter subjected to the action or a metal-surfaced pressure roll, the surface temperature of which approximated 500 F.

In both cases there was obtained a fibreboard coated with a firmly adhering fire-retardant resin'sait film of excellent appearance.

Plasticizers (for example p-toluene' suli'cnamide) and pigments may be added to the resin salt solution if desired.

(d) 200 lbs. titanium dioxide (Rutile), 400 lbs. of the fire-retardant resin salt of Example 1(a) and 500 lbs. of alkyd resin (Falkyd No. A-3) were ground in a conventional paint mill and then dispersed in a mixture containing 118 lbs..of Solvesso No. 3 thinner, 3 lbs. of cobalt drier and 6 lbs. of lead drier. The resulting composition is stable on standing and may be shipped and stored if desired.

(c) 11.9 g. of guanidine carbonate and 12.6 g. of melamine were added to 32.4 cc. of aqueous formaldehyde (37%). The ratio or the resin- 11 forming ingredients was thus 2 mole of formaldehyde to 1 mol of combined guanidine carbonate and melamine. The solution was allowed to stand for two hours. Then about 1.5 cc. 01' con- 1 centrated phosphoric acid (85% HiPOl) was added dropwise until the evolution of C02 stopped, and the mixture was agitated continuously and with caution until it became thick. Then 8 cc. of concentrated phosphoric acid (85% Km) was added and heating continued until the mixture gelled. The gel was cut into small pieces, dried at about 100 0., washed in running water iorabout 24 hours (the pH of the wash water was then about 6) again dried and ground in a ball mill. 6.3 g. of the resulting finely ground resin was then dispersed in a solution comprising 50 cc. of 95' ethyl alcohol and 1 g. of ethyl cellulose. The resulting composition is stable. It may be applied to paper, cardboard, fabrics and other combustible materials by immersion, roll coating, brushing, spraying or other suitable means. Upon evaporation of the alcohol and water from the coating, a fire-retardant material is obtained which is coated with'the resin salt bound to it by the ethyl cellulose When the coated side is exposed to flame a fire-retardant and heat-insulating carbonaceous mass is formed.

(1) 12.5 grams of melamine, 12.5 grams oi guanidine carbonate and 35 grams of aqueous formaldehyde (37%) were added to 400 cc. of water. The ratio of the resin-forming ingredients was thus slightly more than 2 mole of formaldehyde to 1 mol of combined melamine and guanidine. To this mixture 12.5 grams of concentrated phosphoric acid (85% HaPOO was added gradually. Samples of lightweight fabric were dipped into an impregnating bath containing the above liquid composition to which small quantities (for example less than 5% of the weight of the composition) of a plasticizer, such as for example paratoluene sulionamide, or of urea, may be added. The impregnated fabric is squeezed and then placed in an oven at. 95 C. for drying and curing for approximately 90 minutes. The treated fabric is substantially flameproof.

The aqueous resin dispersion of Example 1(a) was used as an adhesive to bond (1) paper to paper. (2) paper aswood, and.(3) wallpaper to insulation board. These materials were bonded by brushing the aqueous resin salt dispersion on both suriaces, pressing the suriaces together and'curing by heat.

(h) To enhance the bonding properties a mixture of dry wheat paste and water containing 5 to by weight oi dry wheat paste, made to the consistency of a fluid paste (as conventionally used in hanging wallpaper) was mixed in equal parts with the aqueous resin dispersion of Example I(c) and used as in Example Hg). An improved bond was obtained particularly when wallpaper was bonded to the fibreboard.

A comparison of fire tests on the treated materials 01' Examples 1(a) and 10:) with fire tests on controls in which the adhesive was the wheat paste of Example 100 containing no resin salt showed a marked improvement in fire resistance of the materials of Examples 1(a) and 101) over aqueous formaldehyde (37%). The ratio of the resin-forming ingredients was thus slightly more than 2.1 mol: of formaldehyde to 1 mol of com- I 12 bincd urea and guanidine carbonate. The solution was stirred without external heating 'ior 35 minutes and an initial slight rise in temperature (to 51 C.) was noted. Then 22.! cc. of concentrated sulfuric acid (sp. gr. 1.84) was added in small portions with continued stirrin until the evolution of CO: stopped. This solution may be used on combustible materials as described in Examples 10;) and 1(a); or the solution may be heated for about 100 minutes on a steam bath until it becomes viscous and may then be dried at about 120 C. to constant weight. The resulting white, heat-cured solid resin sulfate may be ground to any desired mesh size, washed free of water-solubles, and may then be dispersed in a solvent containing a film-forming agent. as illustrated in Examples I(d) and I(e).

Example III.-25.2 g. of melamine and 23.8 g. of guanidine carbonate were added to 64.4 g. of aqueous formaldehyde (37%). The ratio of the resin-forming ingredients was thus 1.94 mols of formaldehyde to 1 mol of combined melamine and guanidine carbonate. The mixture was stirred and 9 cc. or concentrated sulfuric acid (sp. gr. 1.75) was added in small portions. At the end of the addition, no more CO: was liberated and the pH had dropped to about 5. This composition may be applied to combustible materials as described in Examples 1(1)) and 1(0). Or the mixture may then be heated on a steam bath and rapidly gelled at the end of five minutes. It may then be dried at C. until its weight remains constant. This product possesses marked fire-retardance and potential heat-insulating properties.

Example IV.-18.1 g. of m-phenylenediamine dihydrochloride, 7.3 g. of concentrated H01 (36%) and 50 cc. of water were agitated at room temperature and 12 g. of aqueous formaldehyde were added. The temperature of the mixture rose to about 45 C. and a dark colored resin settled out almost immediately. This solid resin hydrochloride was separated from the solution and dried at 105 C. for 18 hours.

Example V.-18.1 g. of m-phenylenediamine dihydrochloride, 8.4 g. oi dicyandiamide, 1.7 g. of concentrated HCl and '70 g. 01 water were heated on a steam bath for 24 hours to form a solution of biguanidylbenzene hydrochloride. This solution was cooled to 50 C. and a mixture of 36.2 g.of m-phenylenediamine dihydrochloride and 3.4 g. of concentrated HCl was added. This mixture was allowed to cool to 30 C. and 52.7 g. of aqueous formaldehyde (37%) were then added slowly. Almost instantly a gel was formed and the tem perature rose to about 80 C. The dark solid resin hydrochloride was dried at 103 C. for 18 hours. This resin hydrochloride showed very marked fire-retardance and resistance to combustion in the furnace test. A porous carbonaceous heatinsulating mass iorms on exposure to 750 C. in the furnace. The mass is reasonably resistant to combustion.

The products of Examples IV and V are primarily suitable for use in conjunction with filmiorming agents as described in Examples lid) and 1(a) Example VI.9.4 g. of phenol, 14.6 g. of triethylene tetramine and 24.3 g. of aqueous tormaldehyde (37%) were carefully mixed with external water cooling; 25 g. of aqueous formaldehyde were then added and the mixture was heated on the steam bath until it gelled. The gel was dried at C. This basic resin is inflammable. when it is reacted with about 3 milli-- aesaeto resin it forms a resin salt of greatly reduced inflammability which is, in conjunction with a filmforniing agent and a solvent, valuable as a fireretardant and potential heat-insulator.

Example VII.-12 g. of triethylene tetramine, 25 g. H3PO4 (85%), 35 g. aqueous formaldehyde (37%) and 125 g. of acetone were refluxed for 1 hour. The light acetone layer was separated from the heavier viscous resinous layer formed. The viscous polymer may be applied to combustible materials, before or after curing by heat to form a fire-retardant coat.

It should be noted that the solid resin salt of this invention may also be used to form molded or otherwise fabricated, substantially non-in flammable articles, or may be used as a dust to protect combustible materials against fire.

We claim:

1. An article of manufacture comprising a base member having as a fire retardant protective surface, an adherent continuous dry coating com-- prising a reaction product of a basic anion-exchange resinous co-condensation product of a weakly basic derivative of cyanamide selected from the group consisting of urea, thiourea, dicyandiamide and melamine, a strongly basic derivative oi cyanamide selected from the group consisting of guanidine and substituted guanidine and formaldehyde with the formaldehyde being in a proportion of at least 1% mols to 1 mol'oi the combined content of said cyanamide derivatives, and at least 2 milliequivalents per gram of said resinous co-condensation product of a strong non-oxidizing inorganic acid having a dissociation constant of at least illsaid coating, when heated to an elevated temperature, being converted into a heat-insulating carbonaceous mass.

2. An article of manufacture as defined in claim 1, wherein the weakly basic derivative of cyanamide is urea and the strongly basic derivative of cyanamide is guanidine.

3. An article of manufacture as claimed in claim 1, wherein the weakly basic derivative of 6. An article of manufacture comprising a base' member having as a fire-retardant protective surface, anadherent dry film of an organic filmforming bonding agent in continuous phase having dispersed therethrough a finely divided reaction product of a basic anion-exchange resinous oo-condensation product of a weakly basic derivative of cyanamide selected from the group consisting of'urea, thiourea, dicyandiamide and melamine, a strongly basic derivative of cyanamide selected from the group consisting of guanidine and substituted guanidine and formaldehyde with the iormaldehyde being in a proportion of at least 1% mols of formaldehyde to 1 mol of combined content of said cyanamide derivatives, and at least two milliequivalents per gram of said resinous co-condensation product of i4 dissociation constant of'at least 10 said coating, when heated to an elevatedntempersture,

being converted into aheat-insulating carbona-- ceous mass.

7. A liquid film-forming composition capable of imparting fire retardant properties to combustible materials when applied thereto and dried thereon, comprising a room temperature liquid mixture of incompletely polymerized basic-anionexchange-co-condensation resin-forming ingredients consisting essentially of a weakly basic derivative of cyanamide selected from the group consisting of urea, thiourea, dicyandlamide and melamine, a strongly basic derivative of cyanamide selected from the group consisting of guanidine and substituted guanidine and an aqueous formaldehyde solution with the formaldehyde being in a proportion of at least about 1% mols of formaldehyde to 1 mol of combined content of said cyanamide derivatives, and at least 2 milliequivalents per gram solids of said resin-forming ingredients of a strong non-oxidizing inorganic acid having a dissociation constant of at least Illsaid composition in the form of a dried film being converted by heat at elevated temperature into a heat-insulating carbonaceous mass.

8, A liquid composition as claimed in claim 7, wherein the resin-forming ingredients comprise urea, guanylurea and formaldehyde.

9. A liquid composition as claimed in claim 7, having, as an additional ingredient. a carbohydrate and wherein the inorganic acid is phosphoric acid.

10. A liquid composition as claimed in claim 7 having, as an additional ingredient, an adhesive.

11. A liquid paint capable of imparting fire retardant properties to combustible materials upon application or said paint thereto, comprise ing a liquid organic film-forming vehicle having suspended therein in dispersed phase a finely divided reaction product of a basic anion-exchange resinous co-condensation product of a weakly basic derivative of cyanamide selected from the group consisting oi urea, thiourea, dicyandiamide and melamine, a strongly basic derivative of cyanamide selectedirom the group consisting of guanidine and substituted guanidine and formaldehyde with the formaldehyde being in a proportion of at least about 1% mols of formaldehyde to 1 mol of combined content of said cyanamide derivatives, and at least 2 milliequlvalents per gram of said co-condensation product of a strong non-oxidizing inorganic acid having a dissociation constant of at least 10 said paint in the form of a dried film being converted by heat at elevated temperature into a heat-insulating carbonaceous mass.

12. A paint as claimed in claim 11 having, as additional ingredients, a carbohydrate and a paint pigment.

13. A paint capable of imparting fire retardant properties to combustible materials, comprising an intimate mixture of a cellulosic bonding agent and a finely divided reaction product of a basicanion-exchange resinous co-condensation product of urea, guanylurea and formaldehyde with the formaldehyde being in a proportion of at least about 1% mols of formaldehyde to 1 mol of a strong non-oxidizing inorganic acid having a sulating carbonaceous mass.

is 16 t, Name a. e

14. A paint as claimed in claim 13, wherein Number the cellulosic bonding agent is ethyl cellulose. 2,368,451 DAlelIo Jan. 30,

WAL'I'ER JUDA. 2,377,867 D'Alelio June 12, 1

GRINNELL JONES 2,402,384 Eastes JIAIIB 1g, 2,418,525 Pollak pr. HAW ALTMAN 5 2,461,538 Fischer Feb. 15, 1949 REFERENCES CITED 2,482,756 Ford I I Sept. 2'7. 1949 The following references are a! record in the 2,501,927 Block M 1950 file Of this patent: I 0 FOREIGN PATENTS UNITED STATES PA'I'ENTS Number Country J n ri lgas umbe' Date 486,766 Great Britain une 1 658 5 97 Orig??? Feb. 7, 1923 566,789 Great Britain Jan. 15, 1945 1,860,097 H 888 May 2 1 QTHER REFERENCES,

25 m Myers Ind. and Eng. Chem, vol. 33, pages 21251334 Swain LII .1"--- July 29. 1941 swam June 9, 1942 Certificate oi Correction Patent No. 2,628,946 February 17, 1953 WALTER JUDA ETAL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 5, line 1, for 2,236,086 read 2,362,086; column 7, line 35, for that portion of the forxpula reading NI-I read NE}; line 38, for dicyandiamide read dicyandz'amv'dine; column 9, line 17, for paintoing read painting;

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Ofiice."

Signed and sealed this'2nd day of June, A. D. 1953.

moms F. MURPHY,

Assistant Gammz'ssioner of Patents. 

7. A LIQUID FILM-FORMING COMPOSITION CAPABLE OF IMPARTING FIRE RETARDANT PROPERTIES TO COM BUSTIBLE MATERIALS WHEN APPLIED THERETO AND DRIED THEREON, COMPRISING A ROOM TEMPERATURE LIQUID MIXTURE OF INCOMPLETELY POLYMERIZED BASIC-ANIONEXCHANGE-CO-CONDENSATION RESIN-FORMING INGREDIENTS CONSISTING ESSENTIALLY OF A WEAKLY BASIC DERIVATIVE OF CYANAMIDE SELECTED FROM THE GROUP CONSISTING OF UREA, THIOUREA, DICYANIDIAMIDE AND MELAMINE, A STRONGLY BASIC DERIVATIVE OF CYANAMIDE SELECTED FROM THE GROUP CONSISTING OF GUANIDINE AND SUBSTITUTED GUANIDINE AND AN AQUEOUS FORMALDEHYDE SOLUTION WITH THE FORMALDEHYDE BEING IN A PROPORTION OF AT LEAST ABOUT 1 2/3 MOLS OF FORMALDEHYDE TO 1 MOL OF COMBINED CONTENT OF SAID CYANAMIDE DERIVATIVES, AND AT LEAST 2 MILLIEQUIVALENTS PER GRAM SOLIDS OF SAID RESIN-FORMING INGREDIENTS OF A STRONG NON-OXIDIZING INORGANIC ACID HAVING A DISSOCIATION CONSTANT OF AT LEAST 10-3, SAID COMPOSITION IN THE FORM OF A DRIED FILM BEING CONVERTED BY HEAT AT ELEVATED TEMPERATURE INTO A HEAT-INSULATING CARBONACEOUS MASS. 